Switch mechanism for fire alarms



Patented June 7, 1949 UNITED STATES PATENT OFFICE 2,472,266 SWITCH MECHANISM FOR FIRE ALARMS Maxime E.. Ouellette, Macwahoc, Maine Application July 7, 1948, Serial No. 37,373

(Cl. :N- 142) 11 Claims. 1

My invention relates in general to a switch device for re alarm systems, and particularly to an alarm device adapted to be installed in a chimney or like place to automatically detect and signal the presence of a fire or excessive temperature conditions, such as that shown and described in my co-pending application, Serial Number '703,441 filed October 15, 1946.

The principal object of my invention is to provide a switching device oi such design that the working parts thereof may be easily and quickly removed for inspection and cleaning without having to disturb any of the electrical connections or having to use tools of any sort.

Another object is to provide a device having a stationary contact plate provided with two oppositely arranged contact elements.

Another object is to provide a device having a reciprocating rod carrying a movable contact member for engagement with either of the stationary contact elements.

A further object is to provide a movable contact member of unsymmetrical form which shall maintain the contact members in working positions, but which, upon rotation, will permit the alarm rod to be readily disassembled without the use of any tools.

A further object of my invention is to provide contacts of ample size for long wear, the stationary surfaces having edge formation thereby resulting is a self-cleaning action between the co-acting surfaces, and thus assuring long carefree service.

Furthermore, the control rod and the rod sheath with their contact members may be readily removed for inspection without energizing the alarm system, and such removability permits the insertion of a new fusion element and an inspection of the contacts before the rod and sheath are reinserted in place within the housing tube.

The above objects and advantages have been accomplished by the device shown in the accompanying drawings of which:

Fig. 1 is a sectional view of my device installed therein;

Fig. 2 is an enlarged sectional view of the housing tube in place within the chimney and with parts of the device removed therefrom;

Fig. 3 is an enlarged longitudinal sectional view of the assembled device;

Fig. 4 is a tranverse sectional view taken on line IV--IV of Fig. 3;

Fig. 5 is a fragmentary plan view of the front end of the alarm rod and rod sheath in assema chimney showing the inner end thereof.

bled positions but removed from the housing tube; and,

Fig. 6 is a fragmentary plan view of the inner end of the alarm rod and rod sheath, showing the fuse element in place.

My device comprises an annular housing tube I0 which is designed to extend through a chimney II, as represented in Fig. 1 of the drawings. A housing flange I2 is secured to the outer end of the housing tube and is brought into contact with the outer face of the chimney thereby acting as a face plate to position the tube. This tube is permanently secured in place within the chimney by any suitable means and is not to be removed during inspection or when renewing a lruse element. The flange I2 is formed with an outwardly extending detent plate I3 which projects over the switch mechanism, to be hereinafter described.

rod sheath I4 of my device. This sheath cornprises an outer member I5 which is loosely fitted into the housing tube, and an inner member I6 which extends into the .outer member I5 from The -inner member I5 is closely iitted into the outer member and is secured against relative axial movement therewith. The outer end of the inner member extends to a point substantially midway the length of the outer member, thereby providing a shoulder which acts as a stop, to be hereinafter described. The outer member of the rod sheath has a sheath flange 2| permanently secured to the outer member thereof which serves as a stop for engagement with the housing flange I2 when the sheath is assembled with the housing tube.

An alarm rod 22 is slidably disposed within the rod sheath I4. This rod extends through the sheath having its front end 23 positioned beyond the iront end of the inner member I6 of the rod sheath when it is set and made ready for operation. with which a fuse element 25 is engaged. This fuse element, as shown in Fig. 6, extends beyond the outer contour lof the rod and bears against the inner end 26 of the inner member I6 of the rod sheath, thereby keeping the end of the rod extended beyond the sheath under normal conditions. The rod is provided with an outer portion 30 of reduced d-iameter upon which is mounted a helical spring 3I. A spring collar 32, is slidably disposed upon this portion of the rod, and it is so proportioned as to bear against the stop shoulder 20 formed at the outer end oi the Extending through the housing tube I0 is the This end is provided with a fuse slot 24- inner member i6 where it is held by the spring when under compression. A movable Contact member 33 i-s mounted upon the reduced portion 3D of the rod and is iixed against relative axial movement upon the rod by a pin Sei or other suitable means. This contact member is of substantially the same diameter as the spring collar 32 and loosely ts into the outer end of the outer member l of the rod sheath where it serves to support the outer end of the rod. This contact member serves as a stop` for the outer end of the spring Si, thereby serving to keep the spring under compression when the contact member is held in place by the fuse element. A push but' ton 3l is provided at the outer end of the alarm rod, whereby it may be manually actuated inwardly to test the device.

The switch mechanism of my device comprises a stationary contact plate 35 which is carried by the bottom wall 36 of the sheath flange 2l. This wall-'is provided with an upwardly extended end wall 4l). The contact plate is secured in place to the bottom wall by means of a suitable fastening device such as a rivet lil. A suitable insulating bushing i2 being placed around the rivet where it passes through the bottom wall, and suitable sheets of insulating `material d3 being placed on both sides of the bottom wall so as to completely insulate the contact plate and the rivet from the wall. lAny suitable type of electrical terminal such as the :clip il@ is secured to the bottom wall by means of the rivet di. The contact plate 35 is provided with a contact element de at one end thereof and with a contact element i6 at the other end thereof. Each of these elements is formed by an upwardly extending end of the contact plate' and the ends are bent inwardly toward each other, as clearly shown in the drawings, whereby edge contact surfaces are provided. Engageable with these spaced contact elements ta'ct plate 5E! carried by the movable contact member33. This plate may be brought into engagement with the contact element l5 for testing purposes when the rod is manually pushed inwardly, and is brought into contact with the element i6 when the fuse element releases the alarm rod. When the alarm rod is released, the spring `3| causes the movable plate to be quickly and forceably brought into contact with the contact element d5 which quick action will bring the contact surfaces together in such a manner that any accumulation of foreign matter on suchfsurfaces will be'removed'. This action is facilitated by the inward `inclination lof the ends of the contact plates thereby providing the relatively sharp edge contact surfaces hereinbefore described.

As shown in Fig. 4, the movable contact plate is of unsymmetrical design and is provided with av relatively wide upper end 5l which is relatively close to the detent plate i3 of the housingr tube, whereby any tendency of the alarm rod to rotate will be restrained. The lower end 52 of the contact plate serves as a contact member for engagelment with the contact elements .d5 and it of the stationary plate. By making the movable Contact plate unsymmetrical in shape, it is possible Vby rotation of the plate through substantially 90 (as shown in dot and dash lines in Fig. 4) toicause it' to clear the Contact element et', thereby perlmitting the disassembling of the alarm rod from the rod sheath.; 'So' as to enclose and protect the switch mechanism of my device, provide a vcasing hood 41 having side walls 53 and an end' wall 55.- The side walls are so designed as to rest upon lridges is a movable con- 54 provided by the side edges of the bottom wall 36 of the sheath flange and at each side of the front wall till thereof.

The inner edges of these side walls contact with the sheath flange 2l and the upper edge oi the end wall contacts the detent plate I3 when the hood is in position. The outer wall is formed with an aperture 56 `for the reception of the reduced portion 3B of the alarm rod. Whenthealarm rod and rod sheath are in assembled positions, as shown in Fig. 3, the upper edge of the outer wall of the casing hood will rest behind the detent ridge Il of the detent flange and thereby be held in position. When assembling the parts there is suiiicient resiliency in the detent plate to permit the wall 55to pass under the ridge.

As shown in Fig. 1, my device may be connected up in any suitable circuit which may comprise a battery (il) and a suitable audible alarm lil. The alarm, battery, and switch device are connected in 'well known manner by suitable wiring, as show-n. Inv order to provide a ground connection for the circuit, a terminal clip 62 is secured to and in' Contact with the bottom wall it of the sheath flange.

f When the device is to be set and made ready for operation, as shown in Fig. 3, the alarm rod is first inserted into the *.rod sheath, the movable Contact plate till' being positioned on its side for passage over the contact element Alt, and the rod is then pushed into the sheath against the compression of the spring by pressure exerted upon the push button untilr the slot 23dk isY exposed at the inner end of the sheath, whereupon a fuse element is inserted within the slot and the manual pressure upon the bottom is released. The fuse element will thereupon be tightly held between the wall of the slot' and the inner end of the sheath by the compressive" action ofthe spring. The alarm rodis then rotated within the rod sheath until the end 52 of the contact'plate is in registrable positioniwith the contactv elements i5 and 46.. The assembled rod-and rod sheath are then inserted into the stationary housing tube il? and the casing'rod 41 is sprung under and beyondthe detent ridge il' .thereby holding the device in assembled position.

It will be obvious from the foregoing, that when abnormalV conditions occur in-the chimney, or other place of use, such asl a fire or an abnormally high temperature, the, fuse element 25 will melt, thus. releasingv .the alarm rod. and permitting it to be moved axially under the action ofthe Spring 3i: and-'to thereby'bring thecontactplate 50, forceably against the contact element 46, thereby closing'the. circuit shown in Fig'. 1 and giving the alarm.

When it is desired to test the device to ascertain whether everything is in working order, it is only necessary to manually operate the push button 3'1 inwardly against the tension of the spring 3l until the end 52lof vthe Contact plate .59 engages the contact element'd ofthe-'stationary contact plate, whereupon the. electric circuit will be closed and the signal'lv operated. Owing to the fact that the fuse slot 24e is'normally in horizontal position there will .be no tendency Vfor the fuse element 25 to' become disengaged from the slot.

It will be obvious from the foregoing, that the entire. assembled switch mechanism may be removed from the housing by simply pulling the same 'outwardlyagainst the yieldable .engagement of the detent ridge I'l with. the upper edge ofthe. casing hood. This maybe accomplished without the use of tools and without disturbing any of the electrical contacts or wires extending thereto. After inspection, the entire assembly may be replaced in reverse manner. Should it be desired for any reason to remove the alarm rod 22 for its sheath`l4, it is only necessary to push inwardly upon the push button 31 to release the fuse element 25 which may then be easily removed from its engaged slot 24, whereupon by rotation of the rod through substantially 90 to release the contact plate 50 from the contact element 45, the entire rod may be withdrawn from the sheath.

Obviously, some modifications of the details herein shown and described may be made without departing from the spirit of my invention or the scope of the appended claims; and I do not, therefore, Wish to be limited to the exact embodiment herein shown and described.

What is claimed is:

1. A switch device for an electrically operated i'lre alarm system, comprising a stationarily arranged housing tube, a tubular rod sheath removably carried by said tube, oppositely spaced stationary electrical contact elements carried by and insulated from said sheath, a contact rod slidably carried by said sheath, a contact member xed to and movable with said rod, said member being engageable with either of said opposed contact elements upon reciprocation of said rod, a spring mounted upon said rod for urging said contact member toward one of said elements, said spring permitting said member to be manually forced into contact with the opposite element, and a fusible element carried by said rod for maintaining said spring under tension, whereby said movable contact member will be automatically released under predetermined temperature conditions and forced against said rst mentioned contact element.

2. A switch device for an electrically operated fire alarm system, comprising a stationarily arranged housing tube, a tubular rod sheath removably carried by said tube, oppositely spaced stationary electrical contact elements carried by and insulated from said sheath, a contact rod slidably carried by said sheath and having its inner end extensible beyond the inner end of said sheath, a contact member fixed to and movable with said rod, said member being engageable with either of said opposed contact elements upon reciprocation of said rod, a spring mounted upon said rod for urging said contact member toward one of said elements when the inner end of said rod is extended beyond said sheath, said spring permitting said member to be manually forced into contact with the opposite element, and a fusible element carried by said rod :for maintaining said rod in end-extending position, whereby said movable contact member will be automatically released under predetermined temperature conditions and forced against said first mentioned contact element.

3. A switch device for an electrically operated re alarm system, comprising a stationarily arranged housing tube, a tubular rod sheath removably carried by said tube, a stationary contact plate carried by and insulated from said sheath, said plate having its end bent to form oppositely arranged spaced contact elements, a contact rod slidably carried by said sheath, a contact member xed to and movable with said rod, said member being engageable with either of said opposed contact elements upon reciprocation of said rod, a spring mounted upon said rod for urging said contact member toward one of said elements, said spring permitting said member to be manually-forced into contact with the opposite element, and a fusible element carried by said rod for maintaining said spring under tension, whereby said movable contact member will be automatically released under predetermined temperature conditions and forced against said first mentioned contact element.

4. A switch device for an electrically operated re alarm system, comprising a stationarily arranged housing tube, a tubular rod sheath removably carried by said tube, a stationary contact plate carried by and insulated from said sheath, said plate having its end bent at an acute angle to the base to form oppositely arranged spaced contact elements, a contact rod slidably carried by said sheath, a contact member fixed to and movable with said rod, said member being engageable with either of said opposed contact elements upon reciprocation of said rod, a spring mounted upon said rod for urging said contact member toward one of said elements, said spring permitting said member to be manually forced into contact with the opposite element, and a fusible element carried by said rod for maintaining said spring under tension, whereby said movable contact member will be automatically released under predetermined temperature conditions and forced against said rst mentioned contact element. i

5. A switch device for an electrically operated fire alarm system, comprising av stationarily arranged housing tube, a detent plate carried by said tube and extending outwardly therefrom in a plate substantially parallel with the axis of said tube, a downwardly projecting detent ridge carried by said plate, a rod sheath removably carried by said tube and having a sheath flange arranged substantially perpendicularly to the axis of said rod sheath, a bottom wall extending outwardly from said sheath flange, acasing hood mounted upon said bottom wall and engageable with said detent plate when in assembled position, an alarm rod slidably mounted within said sheath, a fuse element carried by said rod, said fuse serving to hold said rod against axial movement under spring tension and co-acting switch contact elements carried by said rod and said sheath and engageable upon release of said rod by the melting of said fuse element under predetermined temperature conditions.

6. A switch device for an electrically operated fire alarm system, comprising a stationarily arranged housing tube, a rod sheath removably carried by said tube and formed interiorily with a stop, oppositely spaced stationary electrical contact elements carried by and insulated from said sheath, a contact rod slidably carried by said sheath, a contact member fixed to and movable with said rod, said contact member being engageable with said contact elements upon reciprocation of said rod, a helical spring carried by said rod for urging the same axially, and a spring washer slidably mounted upon said rod and engageable with the stop of said sheath, said washer bearing against one end of said spring and said contact member bearing against the opposite end of said spring.

'7. A switch device for an electrically operated iire alarm system, comprising a stationarily arranged housing tube, a detent plate carried by said tube and extending outwardly therefrom, a rod sheath removably carried by said tube and having a sheath flange, a bottom wall extending outwardly from said flange, a stationary contact said tube, and' a-switch mechanism removably carried by said-tube; said mechanism comprising a' rodsheath for insertionl insaid tube, a sheathv flange carried by said sheath, a hood supported by said sheath flange and engageable with said detent flange `when in assembled position, an alarm rod slidably carried by said rod sheath and said' hood, a stationary switch contact carried by said sheath flange, a movable switch conp'late carried 'by and .insulated from 'said' bottom Wall and formed with stationary contact means, an'v alarm rod slidably carried by said yrod sheath, a`mo'vable contact plate'carried by said rod, said contact plate being vof tapered formation, the larger end surface of said plate being' in normal non-rotative engagement with said detent plate and the smaller end thereof :being in position for engagement with said stationary contact means,

whereby when said largerend surface is withl tact carried by said rod and engageable-with saidl drawn beyond the detent plate, said contact plate stationary contact, a'` fuse carried by said rod to may be rotated substantially 90 to permit the hold said contact in open position, and a spring disassembling of the device.u engageable with said rod to force said Contact .l 8. A switch device for an electrically operated togethei` in'circuit closing relation when said fuse fire alarm system, comprising a stationarily ar-v 1'5 melts.

ranged housing tube, av detent plate' carried by said tube and extending outwardly therefrom in a plane substantially parallel with the axis of said tube, and a switch mechanism removably carried by said tube, said mechanismcomprising a rod sheath for insertion in said tube,v latch means carried, by said plate and said sheath to removably hold said switchmechanism within said tube, means for placing said switch mechanism under Spring tension, and a fuse element for holding said switch mechanism in open position and for releasing the same under predetermined temperature conditions. l

.Y 9. A switch device for an electrically operated fire alarm system, comprising ya statonarily arranged v housing tube a detent plate carried by said tube ,and `extending outwardly therefrom in a plane substantially parallel with the axis of said tube, and a switch mechanism removably carried by said tube, said mechanism comprising a rod sheath for insertion in .said tube, a sheath flange carried by said sheath, a hood supported by said sheathflange and engageable with said detentangewhen in assembled position, means 11. A switch device for an electrically operated fire alarm system, comprising a statienarily ar'- ranged housing tube, a detent plate carried by said tube and extending outwardly` therefrom in a plane substantially parallel with the axis of said tube, and a switch mechanism removably carried by said tube, said mechanism comprising a rod sheath for insertion in said tube, a sheath flange carried by said sheath, a hood supported by said sheath ange and engageable with said detent flange when in assembled position, an alarm rod slidably carried lby said sheath, a sta-Y tionary contact plate carried by said sheath and having two oppositely arranged spaced contact elements, a movable switch contact carried by said rod, said movable Contact being disposed between the said stationary contactl elements and engageable with either of them to close said switch mechanism, a fuse carried by said rod for normally holding said switch mechanism in open position, and a spring engageable with said rod to force said contacts together in circuit closing relation when said vfuse melts.

MAXIME E. OUELLETTE.

for placing. said switchmechanism under spring i0 tension, and a fuse element for holding said switch REFERENCES CITED mechanism in Open position and for releasing The following references are of record in the the same under predetermined temperature confue of this patent; A ditions.

10. A switch device for an electrically operated UNITED STATES PATENTS fire .alarm System, comprising a stationarily ar- Number Name Date rangedhousingtube, a detent plate Carried by 1,981,484 Werring Nov. 20 1934 said tube and extending outwardly therefrom in 2,023,377 Werring Dec. 3; 1935 a plane substantially parallel with the axis of Certificate of Correction Patent No. 2,472,266. June 7, 1949. MAXIME E. OUELLETTE It is hereby certied that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 6, line 35, claim 5, for the Word plate read plane; and that the said Letters Patent should be read With this correction therein that the same may conform to the record of the case in the Patent Oce.

Signed and sealed this 8th day of November, A. D. 1949.

[SEAL] THOMAS F. MURPHY,

Assistant 'ommz'ssoner of Patents.

Certificate of Correction Patent No. 2,472,266. June 7, 1949. MAXIME E. OUELLETTE It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: p

Column 6, line 35, claim 5, for the Word plate read plane; and that the said Letters Patent should be read With this correction therein that the same may conform to the record of the case in the Patent OHce.

Signed and sealed this 8th day of November, A. D. 1949.

THOMAS F. MURPHY,

Assistant (lommssz'oner of Patents. 

